The other day I was looking for example drawings to follow that would be used in a real world context as opposed to basic exercise books and I stumbled across a museum archive of the V2 rocket design. Aside from it being German language the first couple of drawings I opened at random seemed to be very well aligned for what I was looking for and I have started drawing up parts in Inventor.
In the following drawing 361D I got a little confused.
In part 1 The vertical shaft that extends through the top does not show any signs of threading in either of the sections cuts and I would have assumed that is was a smooth 4.1 dia. drilled hole. However when I look at the Bottom/Top view? I see two concentric circles representing the hole. I thought this represented a threaded hole. Similar the 4 M4 threaded holes in the sides and the 4 M3 threaded holes in the bottom. (M4 represents a 4 mm diameter thread hole?) When I look at the assembly view and section A-B (Above) I noted that part 3 is supposed to pass through the hole in the top of part 1.
The portion of Part 3 (below) that passes through Part 1 appears to me as it if is a threaded 4 mm diameter shaft due to the M4 designation below it and the double lines for side walls.
The other shaft that is confusing me is in Part 3 and (above) as well. The threaded hole down from the top is annotated as M4 which I interpreted as a 4 mm diameter hole. According to the assembly drawing section A-B and C-D, Part 4 screws in to this portion of Part 3. Part 4 annotates the shaft as being a matching M4 thread. The confusing part for me is the bottom threaded M4 shaft in Part 3 appears to be wider than the threaded M4 hole above it. Further more the bottom/top view of part 3 seem to indicate that the top threaded hole is a match to the 2 mm dia. transverse through hole at the the bottom of the M4 hole.
Am I misinterpreting something here or are these a drawing errors?
I can't really ask the designer what the correct interpretation should be.